This Application claims the benefit of Japanese Application No. 10-152922 filed on Jun. 2, 1998, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a technique for faithfully recording signals played back by various apparatuses, and more particularly, to an information recording apparatus capable of faithfully recording signals even if external disturbances such as vibrations take place.
2. Description of the Related Art
In recent years, discs have been used as recording media for recording and playing back to general audio and video signals and are coming into wide use. Especially, a recorder/player using Mini Discs (MDs) that are magneto-optical discs and capable of easily recording and playing back music data like the conventional audio cassette tape has enjoyed wide acceptance.
A Mini Disc (MD) is contained within a cartridge like a 3.5-inch floppy disc used in personal computers. A MD has the same maximum recording/playback time of 74 minutes as a compact disc (CD). The sampling frequency is 44.1 kHz and quantization is 16 bits, in the same manner as a CD. However, the amount of data is reduced to about one-fifth by a data compression technique known as adaptive transform acoustic coding (ATRAC) in recording the data in a MD.
In ATRAC, signal is quantized by analog-to-digital conversion in the same way as in a CD. The quantized signal is split into given time periods of up to 11.6 ms and Fourier-transformed into the frequency domain to produce a spectrum consisting of about 1000 frequency components. Priorities are given to these frequency components according to the human perceptual characteristics such as the minimum audible loudness characteristics (the minimum audible loudness at each frequency) and the masking effect (i.e., smaller sounds cannot be heard in the presence of a louder sound). In this way, the signal is coded efficiently.
Although the amount of recorded data is reduced to one-fifth, the perceptual sound quality is only slightly inferior to the quality of CDs because data is compressed by making use of the human perceptual characteristics. Since the disc is very small, the current mainstream application for MDs is small-sized portable consumer products such as headphone stereos.
Heretofore, some MD players have been incorporated in non-portable stereo systems including CD players, radio sets, and Karaoke machines. However, so far no recordable in-car audio MD system is available. Where a MD recorder/player is used as a portable MD device (especially, an in-car audio machine), the portable MD device is simply attached to a car audio machine to function as a recordable in-car MD system.
Therefore, where an audio signal played back by a portable CD player, a radio set, a portable audio device, or an in-car audio machine is dubbed by the disc recorder/player (in this case, a portable MD device), if great vibrations are applied to the device during operation of the vehicle, the position (track) on the MD at which the audio signal is to be recorded deviates from the correct position. As a result, information is recorded at incorrect positions on the MD. If information has been previously recorded at incorrect positions, there is a danger that the information is destroyed.
This is especially true for a user table of contents (TOC) area of the MD which allows the user to program in a playback sequence and playback operation. If the user TOC area of the MD is rewritten, and if wrong information is written into the user TOC due to vibrations, playback of dubbed music is hindered. In addition to areas where music was recorded during vibrations, even music recorded in correct areas and which is capable of being played back normally may not be successfully played back.
FIG. 5 shows one example of the structure of the user TOC area of a MD. This user TOC area consists of 4 bytes (587 data areas, for example. A header 1 indicating a sync pattern consisting of 1 byte pattern of all 0""s or 1""s is located at the forefront position of the user TOC area to indicate that it is the user TOC area. Data including the first track number (first TNO)4 of the first recorded tune, the last track number (last TNO)5 of the last tune, used sectors 6, disc serial number (Disc Serial No.) 7, and disc ID 8 are recorded at given address positions. Furthermore, various table pointers (P-DFA to P-TN0255) are recorded in a corresponding table-indicating data portion 2 to correspond recorded tunes to a management table portion 3 (described later).
The management table portion 3 has 255 part tables (01-FF). Each part table can record a start address indicating the starting point of a segment of physically continuous tracks, an end address indicating the end point thereof, information about the track mode of the segment, and link information about if this segment is linked to other segment. The link information includes a part table in which the start address and the end address of a segment to be linked are recorded.
In this way, information about the whole volume (disc) is recorded in the user-TOC (U-TOC) area. The U-TOC area is different from the normal music area (program area). If an incorrect recording is made in a portion of the program area, only that portion of the program area is affected. However, if an incorrect recording is made in the U-TOC area, the whole disc might be made unusable in the worst case. Hence, data is required to be written into the U-TOC area with the highest reliability.
As described thus far, in the conventional recorder, if a recording operation is performed during the presence of great vibrations, erroneous information may be recorded. If erroneous information is recorded while the U-TOC of an MD is being rewritten, the whole MD may be destroyed. This leads to the malfunction of the MD.
Accordingly, the present invention is directed to an improved information recording apparatus that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide an information recording apparatus capable of avoiding erroneous recording even during the presence of great vibrations.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, an information recording apparatus of the present invention includes recording means for recording information onto a recording medium, detection means for detecting a generation of vibration or a possibility of a generation of vibration, and recording control means for prohibiting or suspending recording of the information onto the recording medium on the basis of a detection result of the detection means.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.